Can I use 24 gauge speaker cable?

Hello,
Just like a few have mentioned in this forum or post. You just need several strands. 24AWG Cat 5/6/7 is really good because it is already twisted in the sheathing. You should do about 8 strands per termination. You can terminate them with some banana plugs or even better spades if your speakers can take spades. If not bare wire is the best but the ends will corrode over time. So give yourself about an extra 6” for cutting for redoing the ends every year. You might be supposed how good it sounds. You will get lots of detail. If you want more mid-bass double up on the gauge. Final thought: if you are using non twisted pair then watch videos on how to braid wire to help prevent noise and cross talk. I used very lite gauge wire in the past and it ruined one of my channels on my AVR. Just work your way up to 16 AWG and you will be good. 

You can do a lot of things with a bunch of thin wire.
https://reverb.com/item/14408424-pine-tree-audio-6-foot-rainbow-ribbons-14awg-speaker-cables

My answer is YES.  You can use 24ga. wire on runs of 50+ feet. I have done so through 5 rooms of my parents house.  Pushed with a Wollensak  reel to reel  mono tape player.  Strictly soft background music.  Small oval 8ohm speakers.  Ran for years.  I replace the Wollensak with a mono fm radio.  Knight? KLH? receiver.  Hey! given me a break.  This was back in the 70's.

Yes with agreement to comments about wire impedance and sonic differences.  Let me remind you of this site = HIGHEND+   Thus should you push 300 watts to your MagnaPlanars, much wattage will be dissipated in the resistance of the 22ga. wire.  Heating up the wire. 
Also there are significant Sonic advantages of implementing thicker wire gauges of different materials and technologies.  I confirmed this to myself when I rebuilt a friend's 3 way Sansui speaker from the 70's.  I just by replacing the solid 22ish ga. wire used with at the time "Monster" cable.  8-10ga.?  The longest run of the three was 14" from the crossover to tweeter.  Wow.  What a difference.  Even when driven by my little Nakamichi receiver on my workbench. Crossover was next.  After which I had to get them out of my shop!  Sonically they were approaching new DCM's and Alon's in the sound room. 

Here's a very old table that's been used to gauge speaker wire applications and it's not just for silver speaker wire, which this site happens to sell:http://tempoelectric.com/cables_speaker-cables.htm

You'll see this table used by a lot of old audio sites and it's probably still relevant unless something's been reinvented.

All the best,
Nonoise

Good lord, who comes up with these thread ideas?  Okay, I guess we know who, but still...